May 1995 arXiv papers — page 3

R. G. Crittenden, N. G. Turok

We compute the angular power spectrum of temperature anisotropies on the microwave sky in the cosmic texture theory, with standard recombination assumed. The spectrum shows `Doppler' peaks analogous to those in scenarios based on primordial adiabatic fluctuations such as `standard CDM', but at quite different angular scales. There appear to be excell

Yasuyuki Kachi

We shall investigate flipping contractions from a semi-stable 4-fold $X$ whose degenerate fiber is a union of Cartier divisors which are terminal factorial 3-folds. Especially we shall prove that $X$ is smooth along the flipping locus, and that the flip exists for such contractions.

Takeshi Saito, Tomohide Terasoma

Period integrals arise from the comparison between Betti cohomologies and de Rham cohomologies. In this paper, we give a formula for the determinant of period integrals in terms of the canonical pairing between Picard group of rank 1 realizations and relative Chow group. It is compatible with the similar formula for Galois modules proved by the first author,

Christian V. Forst, Christian Reidys, Jacqueline Weber

We view the folding of RNA-sequences as a map that assigns a pattern of base pairings to each sequence, known as secondary structure. These preimages can be constructed as random graphs (i.e. the neutral networks associated to the structure $s$). By interpreting the secondary structure as biological information we can formulate the so called Error Threshold

S. Ferrara, J. A. Harvey, A. Strominger, C. Vafa

We propose and give strong evidence for a duality relating Type II theories on Calabi-Yau spaces and heterotic strings on $K3 \times T^2$, both of which have $N=2$ spacetime supersymmetry. Entries in the dictionary relating the dual theories are derived from an analysis of the soliton string worldsheet in the context of $N=2$ orbifolds of dual $N=4$ compacti

Nobuo Terasawa, Makoto Hattori

The effect of kick velocity to newly born pulsars on the distribution of $γ$-ray bursters is examined in the context of a disk origin model and a halo model of $γ$-ray bursters. The conversion formula from a 2-dimensional velocity distribution function to a 3-dimensional distribution function is derived and applied to reproduce the distribution function of t

Carl H. Albright, Satyanarayan Nandi

We construct an explicit $SO(10) \times U(1)_F$ model of the Yukawa interactions by using as a guide previous phenomenological results obtained from a bottom-up approach to quark and lepton mass matrices. The global $U(1)_F$ family symmetry group sets the textures for the Majorana and generic Dirac mass matrices by restricting the type and number of Higgs di

A. Muslimov, D. Page

After Michel (1994) introduced a phenomenological picture of `rapid magnetization' of newly born neutron stars (NSs), Muslimov & Page (1995) suggested that the physical conditions accompanying the formation of a NS may result in the surface magnetic field of the NS having a low value (~ 10^8 - 10^9 G) while the bulk of the flux is submerged under the ste

V. A. Rubakov

We develop a model of $(1+1)$-dimensional parent and baby universes as macroscopic and microscopic fundamental closed strings. We argue, on the basis of understanding of strings from the point of view of target $D$-dimensional space-time, that processes involving baby universes/wormholes not only induce $c$-number "$α$-parameters" in $(1+1)d$ action,

M. Crisafulli, A. Donini, V. Lubicz, G. Martinelli

We present results for the Kaon $B$ parameter from a sample of $200$ configurations using the Wilson action and $460$ configurations using the Clover action, on a $18^3 \times 64$ lattice at $\beta=6.0$. A slight improvement of the chiral behaviour of $B_K$ is observed due to the Clover action. We have also compared the results for $B_K$ obtained from two di

A. Stern, I. Yakushin

We find a one parameter family of quadratic Poisson structures on ${\bf R}^4\times SL(2,C)$ which satisfies the property {\it a)} that it is preserved under the Lie-Poisson action of the Lorentz group, as well as {\it b)} that it reduces to the standard Poincaré algebra for a particular limiting value of the parameter. (The Lie-Poisson transformations reduce

G. F. Burgio, M. Baldo, A. Rapisarda, P. Schuck

We study the motion of classical particles confined in a two-dimensional "nuclear" billiard whose walls undergo periodic shape oscillations according to a fixed multipolarity. The presence of a coupling term in the single particle Hamiltonian between the particle motion and the collective coordinate generates a fully selfconsistent dynamics. We consi

D. Cangemi, R. Jackiw, B. Zwiebach

We revisit the quantization of matter-coupled, two-dimensional dilaton gravity. At the classical level and with a cosmological term, a series of field transformations leads to a set of free fields of indefinite signature. Without matter the system is represented by two scalar fields of opposite signature. With a particular quantization for the scalar with ne

Douglas Singleton, Atsushi Yoshida

In this paper we present a model of confinement based on an analogy with the confinement mechanism of the Schwarzschild solution of general relativity. Using recently discovered exact, Schwarzschild-like solutions of the SU(2) Yang-Mills-Higgs equations we study the behaviour of a scalar, SU(2) charged test particle placed in the gauge fields of this solutio

H. J. de Vega

This is a short review on strings in curved spacetimes. We start by recalling the classical and quantum string behaviour in singular plane waves backgrounds. We then report on the string behaviour in cosmological spacetimes (FRW, de Sitter, power inflation) which is by now largerly understood. Recent progress on self-consistent solutions to the Einstein equa

J. Alfaro, P. H. Damgaard

Requiring that a Lagrangian path integral leads to certain identities (Ward identities in a broad sense) can be formulated in a general BRST language, if necessary by the use of collective fields. The condition of BRST symmetry can then be expressed with the help of the antibracket, and suitable generalizations thereof. In particular, a new Grassmann-odd bra

A. V. Antonov, A. A. Belov, K. Chaltikian

We consider lattice analogues of some conformal theories, including WZW and Toda models. We describe discrete versions of Drinfeld-Sokolov reduction and Sugawara construction for the WZW model. We formulate perturbation theory in chiral sector. We describe the spaces of Integrals of Motion in the perturbed theories. We interpret the perturbed WZW model in te

R. J. Crewther

Even the uninitiated will know that Quantum Field Theory cannot be introduced systematically in just four lectures. I try to give a reasonably connected outline of part of it, from second quantization to the path-integral technique in Euclidean space, where there is an immediate connection with the rules for Feynman diagrams and the partition function of Sta

I. Avaliani

In the Born approximation, as in the next-to-leading order approximation, Single lepton production $p\bar{p}\rightarrow l^{\pm}νX$ at Fermilab Tevatron is discussed. The effects of non standard model physics ($W'$ - production) are also considered. It was shown that $2\rightarrow 3$ subprocesses play important role when a high transverse momentum cut on

Michael A. Doncheski

It has recently been noticed that heavy quark ($Q$) and gluon ($g$) fragmentation to heavy quarkonium states ($Q\bar{Q}$) can be calculated in perturbative QCD. This technique allows for the inclusion of a subset of higher order corrections to quarkonium production which dominates at large transverse momentum. A comparison will be presented between the new c

Eugene Golowich

We discuss prospects for detecting the two charm-related phenomena of $D^0$-${\bar D}^0$ mixing and weak radiative decays of $D$ mesons ({\it e.g.} $D\to K^* + γ$). A general update of particle-antiparticle mixing for the pseudoscalar mesons is presented and the dynamics of mixing is reviewed, with application especially to the $D^0$-${\bar D}^0$ system. The

Michael Krämer

Heavy quarks are copiously produced in two-photon collisions at $e^+e^-$ colliders. The theoretical predictions including QCD radiative corrections are compared to recent experimental data on $γγ$ production of charm quarks at PETRA, PEP, TRISTAN and LEP. Photoproduction of heavy quarks at HERA is an important tool to measure the gluon distribution in the pr

M. Cacciari, M. Greco, M. L. Mangano, A. Petrelli

We present in this work a study of large-\pt\ charmonium production in hadronic collisions. We work in the framework of the factorization model of Bodwin Braaten and Lepage, thereby including the color octet production mechanism, and extract the values of the necessary nonperturbative parameters from a comparison with the most recent data from the Fermilab 1

D0 Collaboration

The inclusive cross sections times leptonic branching ratios for W and Z boson production in PbarP collisions at Sqrt(s)=1.8 TeV were measured using the D0 detector at the Fermilab Tevatron collider: Sigma_W*B(W->e, nu) = 2.36 +/- 0.07 +/- 0.13 nb, Sigma_W*B(W->mu,nu) = 2.09 +/- 0.23 +/- 0.11 nb, Sigma_Z*B(Z-> e, e) = 0.218 +/- 0.011 +/- 0.012 nb, Sigma_Z*B(

V. Loreto, L. Pietronero, A. Vespignani, S. Zapperi

We introduce a Renormalization scheme for the one and two dimensional Forest-Fire models in order to characterize the nature of the critical state and its scale invariant dynamics. We show the existence of a relevant scaling field associated with a repulsive fixed point. This model is therefore critical in the usual sense because the control parameter has to

D. M. McAvity, H. Osborn

The implications of restricted conformal invariance under conformal transformations preserving a plane boundary are discussed for general dimensions $d$. Calculations of the universal function of a conformal invariant $ξ$ which appears in the two point function of scalar operators in conformally invariant theories with a plane boundary are undertaken to firs

Zlatko Tesanovic

A new description is proposed for the low-field critical behavior of type-II superconductors. The starting point is the Ginzburg-Landau theory in presence of an external magnetic field H. A set of fictitious vortex variables and a singular gauge transformation are used to rewrite a finite H Ginzburg-Landau functional in terms of a complex scalar field of zer

P. Singha Deo

It has been shown[19] that in a loop of length u to which a single stub of length v is attached (fig. 1 in ref. 19), the parity effect is completely destroyed when v/u$>2$. It was also shown that such minute topological defects (v/u$<<1$) act as singular perturbations. However ref. 19 studies the effect of a single topological defect and says that for v/u$<<

Z. Y. Weng, C. Y. Chen, D. N. Sheng

By explicitly tracking the Marshall sign, a phase string induced by hopping is revealed in the one-hole-doped $t-J$ model. It is rigorously shown that such a phase string cannot be eliminated through low-lying spin excitations, and it either causes the spectral weight $Z=0$, or leads to the localization of the doped hole. Implications for finite doping are a

Mohamed Azzouz, Claude bourbonnais

A mean-field theory of the spin Peierls systems based on the two dimensional dimerized Heisenberg model is proposed by introducing an alternating bond order parameter. Improvements with respect to previous mean-field results are found in the one-dimensional limit for the ground state and the gap energies. In two dimensions, the analysis of the competition be

Joseph Rudnick, Robijn Bruinsma

A domain in a Langmuir monolayer can be expected to have a shape that reflects the textural anisotropy of the material it contains. This paper explores the consequences of XY-like ordering. It is found that an extension of the Wulff construction allows for the calculation of two-dimensional domain shapes when each segment of the perimeter has an energy that

F. Dalfovo, A. Fracchetti, A. Lastri, L. Pitaevski

The probability of evaporation induced by $R^+$ and $R^-$ rotons at the surface of superfluid helium is calculated using time dependent density functional theory. We consider excitation energies and incident angles such that phonons do not take part in the scattering process. We predict sizable evaporation rates, which originate entirely from quantum effects

F. Dominguez-Adame, A Sanchez, E Diez

We study quantum diffusion of wavepackets in one-dimensional random binary subject to an applied electric field. We consider three different cases: Periodic, random, and random dimer (paired) lattices. We analyze the spatial extent of electronic wavepackets by means of the time-dependent inverse participatio ratio. We show that the delocalized states recentl

Joonhyun Yeo, M. A. Moore

We calculate the renormalized quartic vertex function of the Ginzburg-Landau model for a superconducting film in a magnetic field by summing an infinite subset of diagrams, the so-called parquet graphs. Using this non-perturbative solution, we obtain the structure factor of the two-dimensional vortex liquid. We find growing crystalline order in the system as

Walter Kob, Hans C. Andersen

We have performed a molecular dynamics computer simulation of a supercooled binary Lennard-Jones system in order to compare the dynamical behavior of this system with the predictions of the idealized version of mode-coupling theory (MCT). By scaling the time $t$ by the temperature dependent $α$-relaxation time $τ(T)$, we find that in the $α$-relaxation regim

Nobuo Furukawa

Using the Kondo lattice model with classical spins in infinite dimension, conductivity in the perovskite-type $3d$ transition-metal oxide (La,Sr)MnO$_3$ is theoretically studied. Green&#39;s functions as well as spontaneous magnetization are obtained exactly on the Bethe lattice as a function of temperature. Conductivity is calculated from the Kubo formula.

Raphael Blumenfeld

A first-principles statistical theory is constructed for the evolution of two dimensional interfaces in Laplacian fields. The aim is to predict the pattern that the growth evolves into, whether it becomes fractal and if so the characteristics of the fractal pattern. Using a time dependent map the growing region is conformally mapped onto the unit disk and th

I. Dan Melamed

This paper shows how to induce an N-best translation lexicon from a bilingual text corpus using statistical properties of the corpus together with four external knowledge sources. The knowledge sources are cast as filters, so that any subset of them can be cascaded in a uniform framework. A new objective evaluation measure is used to compare the quality of l

Yuko Okamoto, Ulrich H. E. Hansmann

Thermodynamics of helix-coil transitions in amino-acid homo-oligomers are studied by the recently proposed multicanonical algorithms. Homo-oligomers of length 10 are considered for three characteristic amino acids, alanine (helix former), valine (helix indifferent), and glycine (helix breaker). For alanine other lengths (15 and 20) are also considered in ord

H. J. Haubold, A. M. Mathai

The paper is based on lectures on the internal structure and evolution of the Sun. It contains an outline of observational and theoretical elements of the Standard Solar Model, emphasizing also recent research results on solar rotation, magnetic fields, thermonuclear energy generation, and solar activity.

Luis Gonzalez-Mestres

The apparent Lorentz invariance of the laws of physics does not imply that space-time is indeed minkowskian. Matter made of solutions of Lorentz-invariant equations would feel a relativistic space-time even if the actual space-time had a quite different geometry (i.e. a galilean space-time). A typical example is provided by sine-Gordon solitons in a galilean

Ziv Ran

We give a canonical description of the formal moduli space of a vector bundle on a variety; as an application, we prove the closedness of certain differential forms on moduli corresponding to the trace form on the endomorphism algebra of the bundle.

Anders Irbäck, Frank Potthast

See chem-ph/9505003.

Anders Irbäck, Frank Potthast

We study the thermodynamic behavior of a simple off-lattice model for protein folding. The model is two-dimensional and has two different ``amino acids&#39;&#39;. Using numerical simulations of all chains containing eight or ten monomers, we examine the sequence dependence at a fixed temperature. It is shown that only a few of the chains exist in unique fold

R. Calabrese, V. Guidi, P. Lenisa, E. Mariotti

A novel diagnostic method for detecting ordering in one-dimensional ion beams is presented. The ions are excited by a pulsed laser at two different positions along the beam and fluorescence is observed by a group of four photomultipliers. Correlation in fluorescence signals is firm indication that the ion beam has an ordered structure.

John J. Neumann, David Seibert, George Fai

We use a boost-invariant one-dimensional (cylindrically symmetric) fluid dynamics code to calculate $e^+e^-$ production from $ρ^0$ and $ω$ decay in the central rapidity region of a central S+Au collision at $\sqrt{s}=20$ GeV/nucleon. We use equations of state with a first-order phase transition between a massless pion gas and quark gluon plasma, with transit

Ivan Cherednik

We extend the previous paper &#34;Macdonald&#39;s evaluation ... and applications&#34; to the non-symmetric polynomilas recently introduced by Macdonald (as difference counterparts of Opdam&#39;s non-symmetric ones).

Benedikt Bläsi, Lucien Hardy

We describe a gedanken experiment with an interferometer in the case of pre- and postselection in two different time symmetric ways: We apply the ABL formalism and the de Broglie--Bohm model. Interpreting these descriptions ontologically, we get two very different concepts of reality. Finally, we discuss some problems implied by these concepts.

J. Donin

In this paper we introduce two classes of Poisson brackets on algebras (or on sheaves of algebras). We call them locally free and nonsingular Poisson brackets. Using the Fedosov&#39;s method we prove that any locally free nonsingular Poisson bracket can be quantized. In particular, it follows from this that all Poisson brackets on an arbitrary field of chara

Indranil Biswas, Subhashis Nag, Dennis Sullivan

There exists on each Teichmüller space $T_g$ (comprising compact Riemann surfaces of genus $g$), a natural sequence of determinant (of cohomology) line bundles, $DET_n$, related to each other via certain ``Mumford isomorphisms&#39;&#39;. There is a remarkable connection, (Belavin-Knizhnik), between the Mumford isomorphisms and the existence of the Polyakov s

Michael Reisenberger

Ashtekar&#39;s canonical theory of classical complex Euclidean GR (no Lorentzian reality conditions) is found to be invariant under the full algebra of infinitesimal 4-diffeomorphisms, but non-invariant under some finite proper 4-diffeos when the densitized dreibein, $\tilE^a_i$, is degenerate. The breakdown of 4-diffeo invariance appears to be due to the in

Shinya Kanemura, Takao Matsushita

It is known that in the 2+1 dimensional quantum electrodynamics with Chern-Simons term, spontaneous magnetic field induces Lorentz symmetry breaking. In this paper, thermodynamical characters, especially the phase structure of this model are discussed. To see the behavior of the spontaneous magnetic field at finite temperature, the effective potential in the

M. Ardehali

We describe efficient protocols for quantum oblivious transfer and for one-out-of-two quantum oblivious transfer. These protocols, which can be implemented with present technology, are secure against general attacks as long as the cheater can not store the bit for an arbitrarily long period of time.

Y. Iwasaki, K. Kanaya, S. Kaya, S. Sakai

The nature of QCD phase transition is studied with massless up and down quarks and a light strange quark, using the Wilson formalism for quarks on a lattice with the temporal direction extension $N_t=4$. We find that the phase transition is first order in the cases of both about 150 MeV and 400 MeV for the strange quark mass. These results together with thos

D. Deutsch, A. Barenco, A. Ekert

We show that in quantum computation almost every gate that operates on two or more bits is a universal gate. We discuss various physical considerations bearing on the proper definition of universality for computational components such as logic gates.

A. Barenco

We prove the existence of a class of two--input, two--output gates any one of which is universal for quantum computation. This is done by explicitly constructing the three--bit gate introduced by Deutsch [Proc.~R.~Soc.~London.~A {\bf 425}, 73 (1989)] as a network consisting of replicas of a single two--bit gate.

John P. Costella

In this short note, I point out that [p,q] does not equal (i h-bar), contrary to the original claims of Born and Jordan, and Dirac. Rather, [p,q] is equal to something that is *infinitesimally different* from (i h-bar). While this difference is usually harmless, it does provide the solution of the Born-Jordan &#34;trace paradox&#34; of [p,q]. More recently,

Attila Csoto

I show that the solar neutrino fluxes, predicted by standard nuclear and solar physics, can get closer to the experimental observations if one takes the freedom to introduce two free parameters into the model, as it is done in the MSW solution. I point out that the plasma electron capture of Be7 and the He3(He3,2p)He4 nuclear reactions deserve further experi

E. C. Ethridge, S. C. Erwin, W. E. Pickett

A metastable phase of NbN with superconducting Tc=16.4 K was reported recently by Treece and collaborators. The reported structure of the thin film sample deviates from the rocksalt (B1) NbN structure with 25% ordered vacancies on each sublattice (space group Pm3m) and a lattice constant of 4.442 Angstroms. Using full potential electronic structure methods,

M. Bordag, B. Geyer, K. Kirsten, E. Elizalde

We present a direct approach for the calculation of functional determinants of the Laplace operator on balls. Dirichlet and Robin boundary conditions are considered. Using this approach, formulas for any value of the dimension, $D$, of the ball, can be obtained quite easily. Explicit results are presented here for dimensions $D=2,3,4,5$ and $6$.

H. Boschi-Filho, C. Farina

We calculate the partition function of a harmonic oscillator with quasi-periodic boundary conditions using the zeta-function method. This work generalizes a previous one by Gibbons and contains the usual bosonic and fermionic oscillators as particular cases. We give an alternative prescription for the analytic extension of the generalized Epstein function in

Rafael de Lima Rodrigues, Arvind Narayan Vaidya

We construct an integral representation for the momentum space Green&#39;s function for a Neutron in interaction with a straight current carrying wire.

S. Kalyana Rama

Analysing the static, spherically symmetric graviton-dilaton solutions in low energy string and Brans-Dicke theory, we find the following. For a charge neutral point star, these theories cannot predict non trivial PPN parameters, $β$ and $γ$, without introducing naked singularities. We then couple a cosmological constant $Λ$ as in low energy string theory. W

A. Klemm, W. Lerche, S. Theisen

We elaborate on our previous work on N=2 supersymmetric Yang-Mills theory. In particular, we show how to explicitly determine the low energy quantum effective action for $G=SU(3)$ from the underlying hyperelliptic Riemann surface, and calculate the leading instanton corrections. This is done by solving Picard-Fuchs equations and asymptotically evaluating per

A. V. Ramallo, J. M. Sanchez de Santos

We study the realization of the (super) conformal topological symmetry in two-dimensional field theories. The mirror automorphism of the topological algebra is represented as a reflection in the space of fields. As a consequence, a double BRST structure for topological matter theories is found. It is shown that the implementation of the topological symmetry

A. Shafei Deh Abad

In this paper we consider Hamiltonian systems on the quantum plane and we show that the set of Q-meromorphic Hamiltonians is a Virasoro algebra with central charge zero and the set of Hamiltonian derivations of the algebra of $Q$-analytic functions ${\cal A}_q$ with values in the algebra of $Q$-meromorphic functions ${\cal M}_q$ is the Lie algebra $sl(2,A_1(

Ian R. Pinkstone

The nature of duality symmetries is explored in closed bosonic string theory, particularly in the case of a four-dimensional target space admitting a one-parameter isometry. It appears that the S-duality of string theory behaves analogously to the Ehlers&#39; symmetry of General Relativity. Furthermore, it is demonstrated that the O(1,1) target space duality

Will Loinaz, R. Akhoury

We present a QCD-based calculation of the exclusive semileptonic decay Lambda_b -> p l nu-bar. Using the ideas of Heavy Quark Effective Theory, we discuss the factorization of the amplitude. Further, resummed Sudakov effects are put in to ensure a consistent perturbative expansion.

D. de Florian, C. A. Garcia Canal, S. Joffily, R. Sassot

We compare the $Q^{2}$ dependence of the polarized deep inelastic scattering proton asymmetry, driven by the leading order Altarelli Parisi evolution equations, to those arising from fixed order $α_{s}$ and $α_{s}^{2}$ approximations. It is shown that the evolution effects associated with gluons, which are not properly taken into account by the leading order

Rudolph C. Hwa, Jicai Pan

The problem of clusters growth in quark-hadron phase transition in heavy-ion collision is investigated by cellular automata. The system is found to exhibit self-organized criticality with the distribution of cluster sizes having universal scaling behavior.

Rudolph C. Hwa, Jicai Pan

The problem of hadronic cluster production in quark-hadron phase transition in heavy-ion collisions is studied by cellular automata. Previous result on the scaling behavior is extended to include variation in the drift speed. It is also shown that coalescence is more important than growth in generating scaling. A new set of rules is adopted to free the clust

D. Nanopoulos

Recent developments/efforts to understand aspects of the brain function at the {\em sub-neural} level are discussed. MicroTubules (MTs) participate in a wide variety of dynamical processes in the cell, especially in bioinformation processes such as learning and memory, by possessing a well-known binary error-correcting code with 64 words. In fact, MTs and DN

Felix M. Lev

The three well-known forms of relativistic dynamics are unitarily equivalent and the problem of constructing the current operators can be solved in any form. However the notion of the impulse approximation is reasonable only in the point form. In particular, the parton model which is the consequence of the impulse approximation in the front form is incompati

P. A. Henning, E. Quack

Considering the propagation of off-shell particles in the framework of thermal field theory, we present the general formalism for the calculation of the production rate of soft photons and dileptons from a hot plasma. This approach is illustrated with an electrodynamic plasma. The photon production rate from strongly interacting quarks in the quark-gluon pla

T. Asaka, N. Maekawa, T. Moroi, Y. Shobuda

We report first results from the investigation on probing dynamical mechanism of the electroweak symmetry breaking using top quark. We consider the case where the top mass originates from a fermion-antifermion pair condensate, which necessitates (i)strong interaction to cause condensation, and (ii)4-fermi interaction to give top mass. From the observed top m

G. Triantaphyllou

In this work we study the critical behavior and momentum dependence of chirality-flipping fermion 4-point functions in non-abelian gauge theories. Our formalism is based on the Schwinger-Dyson system of equations. Considering the large-N limit of an SU(N) theory simplifies the problem considerably, showing us clearly which Green functions can be non-zero and

W. Bietenholz, A. Pochinsky, U. -J. Wiese

The 2-d $O(3)$-model with a $θ$-vacuum term is formulated in terms of Wolff clusters. Each cluster carries a half-integer topological charge. The clusters with charge $\pm 1/2$ are identified as merons. At $θ= π$ the merons are bound in pairs inducing a second order phase transition at which the mass-gap vanishes. The construction of an improved estimator fo

D. ESPRIU, A. TRAVESSET

We study the implementation of Monte Carlo renormalization group (MCRG) in momentum space. This technique is most efficient when used in combination with a Fourier accelerated Langevin algorithm. As a benchmark we calculate the critical exponents $ν$ and $η$ in the vicinity of both the gaussian and the Wilson fixed point in $λϕ^4_3$. The results are very com

David Kirkby

I describe two methods for studying hadronic backgrounds to prompt photon production with L3, and compare the observed background rates with Monte Carlo predictions. I find that the Monte Carlo models JETSET and HERWIG underestimate the production of isolated neutral hadrons in hadronic Z decays at LEP. By extrapolating results obtained with L3, I estimate t

E. Calzetta, B. L. Hu

We examine from first principles one of the basic assumptions of modern quantum theories of structure formation in the early universe, i.e., the conditions upon which fluctuations of a quantum field may transmute into classical stochastic perturbations, which grew into galaxies. Our earlier works have discussed the quantum origin of noise in stochastic infla

Sandro S. Costa, George E. A. Matsas

We investigate whether inertial thermometers moving in a thermal bath behave as being hotter or colder. This question is directly related to the classical controversy concerning how temperature transforms under Lorentz transformations. Rather than basing our arguments on thermodynamical hypotheses, we perform straightforward calculations in the context of re

Peter Anninos, Richard H. Price, Jorge Pullin, Ed Seidel

A benchmark problem for numerical relativity has been the head-on collision of two black holes starting from the ``Misner initial data,&#39;&#39; a closed form momentarily stationary solution to the constraint equations with an adjustable closeness parameter $μ_0$. We show here how an eclectic mixture of approximation methods can provide both an efficient me

S. Franz, F. Ritort

In this note we study the dynamics of a model recently introduced by one of us, that displays glassy phenomena in absence of energy barriers. Using an adiabatic hypothesis we derive an equation for the evolution of the energy as a function of time that describes extremely well the glassy behaviour observed in Monte Carlo simulations.

M. Quaisser, A. Schadschneider, J. Zittartz

We investigate ground-state properties of two correlated-hopping electron models, the Hirsch and the Bariev model. Both models are of recent interest in the context of hole superconductivity. Applying the Lanczos technique to small clusters, we numerically determine the binding energy, the spin gaps, correlation functions, and other properties for various va

A. De Martino, R. Musto

We describe a $n$ component abelian Hall fluid as a system of {\it composite bosons} moving in an average null field given by the external magnetic field and by the statistical flux tubes located at the position of the particles. The collective vacuum state, in which the bosons condense, is characterized by a Knizhnik-Zamolodchikov differential equation rela

Leticia F. Cugliandolo, Pierre Le Doussal

We study the off-equilibrium dynamics of a particle in a general $N$-dimensional random potential when $N \to \infty$. We demonstrate the existence of two asymptotic time regimes: {\it i.} stationary dynamics, {\it ii.} slow aging dynamics with violation of equilibrium theorems. We derive the equations obeyed by the slowly varying part of the two-times corre

Dragi Karevski, Loïc Turban, Ferenc Iglói

We consider concentric circular defects in the two-dimensional Ising model, which are distributed according to a generalized Fredholm sequence, i. e. at exponentially increasing radii. This type of aperiodicity does not change the bulk critical behaviour but introduces a marginal extended perturbation. The critical exponent of the local magnetization is obta

A. A. Kipchatov, L. V. Krasichkov

The method of reconstruction of an attractor from a set of short time series ({\it clusters}) is proposed and discussed. This method is most useful for correlation dimension estimation of experimental data.

Joseph F. McCarthy, Wendy G. Lehnert

This paper describes RESOLVE, a system that uses decision trees to learn how to classify coreferent phrases in the domain of business joint ventures. An experiment is presented in which the performance of RESOLVE is compared to the performance of a manually engineered set of rules for the same task. The results show that decision trees achieve higher perform

Tetsuya Nasukawa

In a consistent text, many words and phrases are repeatedly used in more than one sentence. When an identical phrase (a set of consecutive words) is repeated in different sentences, the constituent words of those sentences tend to be associated in identical modification patterns with identical parts of speech and identical modifiee-modifier relationships. Th

Gerhard Hummer, Lawrence R. Pratt, Angel E. Garcia

The hydration free energies of ions exhibit an approximately quadratic dependence on the ionic charge, as predicted by the Born model. We analyze this behavior using second-order perturbation theory. This provides effective methods to calculating free energies from equilibrium computer simulations. The average and the fluctuation of the electrostatic potenti

Bernd Hartke

A new strategy for global geometry optimization of clusters is presented. Important features are a restriction of search space to favorable nearest-neighbor distance ranges, a suitable cluster growth representation with diminished correlations, and easy transferability of the results to larger clusters. The strengths and possible limitations of the method ar

John S. Carr, Neal J. Evans, J. H. Lacy, Shudong Zhou

We have observed rovibrational transitions of acetylene and HCN near 13 microns in absorption toward GL2591. We also observed rotational lines of CS, HCN, H2CO, and HCO+. The combined data are analyzed in terms of models with a cloud envelope with density gradients and discrete regions of hot, dense gas, probably near the infrared source. The abundance of HC

T. J. Davidge

Moderately deep near-infrared images are used to investigate the photometric properties and spatial distribution of bright giants near the centers of the core-collapsed globular clusters NGC5946 and NGC7099. The former cluster is located at a low Galactic latitude and is heavily reddened; nevertheless, the K, J-K color-magnitude diagram (CMD) shows a well-de

Arno G. Weiss, Stefan Gottloeber, Thomas Buchert

We investigate the performance of Lagrangian perturbation theory up to the second order for two scenarios of cosmological large-scale structure formation, SCDM (standard cold dark matter) and BSI (broken scale invariance). The latter model we study as a representative of COBE-normalized CDM models which fit the small-scale power of galaxy surveys. In this co

E. Brocato, V. Castellani, V. Ripepi

In this paper we present new CCD investigations of RR Lyrae pulsators in the Oo.I globular cluster M5. B V curves of light for 15 RR Lyrae are presented. With the addition of further 11 curves of light by Storm, Carney and Beck (1991) one is dealing with a sample of 26 well studied cluster pulsators whose properties have been implemented with similar data fo

Hans-Walter Rix, Dennis Zaritsky

We study the azimuthal structure of the stellar disks of 18 face-on spiral galaxies, using K-band photometry to trace the stellar surface mass density. Assuming the disks are co-planar, we characterize their deviation from axisymmetry by the fractional amplitudes, A_i and phases of the azimuthal Fourier components at radii R about the photometric galaxy cent

Timothy J. Ford

Associated to a toric variety $X$ of dimension $r$ over a field $k$ is a fan $Δ$ on $\Bbb R^r$. The fan $Δ$ is a finite set of cones which are in one-to-one correspondence with the orbits of the torus action on $X$. The fan $Δ$ inherits the Zariski topology from $X$. In this article some cohomological invariants of $X$ are studied in terms of whether or not

R. Pandharipande

Let N_d be the number of degree d, nodal, rational plane curves through 3d-1 points in the complex projective plane. The number of degree d>=3, nodal, elliptic plane curves with a fixed (general) j-invariant through 3d-1 points is found to be {d-1 \choose 2}*N_d.

Junichi Iwasaki

We show that the partition function of the Ponzano-Regge quantum gravity model can be written as a sum over surfaces in a $(2+1)$ dimensional space-time. We suggest a geometrical meaning, in terms of surfaces, for the (regulated) divergences that appear in the partition function.